Re: Re: Matrix column access

Raymond Toy <[email protected]> writes:

>>>>>> "Nicolas" == Nicolas Neuss <[email protected]> writes:
>
>     Nicolas> Raymond Toy <[email protected]> writes:
>     >> Not quite sure what you mean by automating the process of making the
>     >> routines available.  Someone has to figure out the function signature
>     >> to tell Lisp how to call it.  And some of the functions take
>     >> characters or strings, and that is very dependent on the Fortran
>     >> compiler.  Same with returning complex values.
>
>     Nicolas> Does this mean that interfacing to Fortran libraries is ill-defined?  Maybe
>     Nicolas> one should use the C-interface of BLAS/LAPACK then?
>
> Perhaps.  Replacing them all would be quite a bit of work, though.  Is
> the C interface just that and you still have to use Fortran for 
> BLAS/LAPACK, so you get another layer?

If one uses clapack, it uses f2c (http://www.netlib.org/clapack/readme).
But I don't know how performance does compare.

> I think the standard used by Matlisp is the standard for the old
> portable f77 compiler, which is used by g77 and Sun f77, so it's not
> so bad.  I suspect that I'm the only one who uses something other than
> g77, and I don't do that very often either.
>
> For the record, Fortran strings are represented as basically C
> strings, and the length of the string is appended to the list of
> parameters.  Functions returning complex values actually insert a new
> parameter into the arg list and this parameter is a pointer to where
> the complex value should be stored.  This is probably how the C
> interface works.
>
> Ray

Ouch, this looks much nastier than I thought.  I googled, and did not find
even a complete C interface to the Fortran BLAS/LAPACK libraries.  In this
case, trying to do an automatic CL interface is probably not very
reasonable.

Thanks for the information,

Nicolas.


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